34 HISTOEICAL SKETCH OF THE [ix. 



there can be little doubt that the burdens imposed 

 on the great estates were increased after the 

 Conquest. 



To insure the safety of the kingdom, for which 

 such scant and unsystematic provision was made by 

 the weak Saxon executive, castles were erected at 

 important strategical points, such as Rochester, 

 Tonbridge, Reigate, Bramber, Clare, &c., as well as 

 on the borders towards Scotland and Wales ; castles 

 which became the residences and were probably 

 built at the expense of the great feudal tenants, 

 aided by forced labour ; and were garrisoned by 

 their retainers. 



Not only was the defence of the kingdom 

 strengthened, and its possession assured, by the 

 erection of fortresses, but the grants made by the 

 Crown were burdened by an obligation on the 

 grantee to furnish, when called upon, a certain 

 number of knights that is, of armed horsemen, with 

 sufficient attendants and provisions for forty days, 

 during which they were bound to serve. According 

 to the number of knights for whose service the grant 

 was made, it was said to consist of so many knights' 

 fees, and to be held by knight-service. 



Those who received grants comprising many 

 manors, retained some of the principal in their own 

 hands, while the rest were granted by them to their 

 followers, or remained in possession of the Saxon 

 owners. These grants also were generally subject 



